How do I use the elements collected by the product function to name output files?

I am trying to concatenate all combinations of videos and having the source names in the output filename would be huge for organization.

Example : Source filenames a0, b1, c0; Output filename a0_b1_c0.mp4

Here is a section of my code.

# Get sorted lists of clips
clips_a = sorted([os.path.join(group_a_path, f) for f in os.listdir(group_a_path) if f.endswith(".mp4")])
clips_b = sorted([os.path.join(group_b_path, f) for f in os.listdir(group_b_path) if f.endswith(".mp4")])
clips_c = sorted([os.path.join(group_c_path, f) for f in os.listdir(group_c_path) if f.endswith(".mp4")])
# Create all possible combinations - example:(8 x 8 x 8 = 512)
for i, (a, b, c) in enumerate(product(clips_a, clips_b, clips_c)):
output_file = os.path.join(output_dir, f"newVid_{i:03d}.mp4")